As the downscaling of semiconductor devices advances, there is an increasing need for downscaling in an EUV lithography process using extra ultraviolet (EUV) light as a light source. A reflective mask in which a light-absorbing pattern is formed is used in the EUV lithography process. In the reflective mask, many reflective layers are used; and a high aspect ratio is realized. It is desirable to improve the quality of such a reflective mask.